1. Field of the Invention
The present invention relates to evaporative coolers designed to distribute cool air currents, having a temperature lower than that of atmospheric air, to a target room without using refrigerant, different from typical air conditioners, and, more particularly, to a regenerative evaporative cooler designed to reduce the temperature of inlet air using latent heat of vaporization of water prior to distributing the air to a target room.
2. Description of the Prior Art
As well known to those skilled in the art, evaporative coolers spray water to air flowing in a channel, thus allowing the water to vaporize absorbing the latent heat from the air and subsequently the air to become cool before it is distributed from the cooler to a target room. Several types of evaporative coolers have been proposed and used in the prior art. For example, Korean Patent Laid-open Publication No. 96-1649, and U.S. Pat. Nos. 3,792,841 and 4,337,216 each disclose a direct-type evaporative cooler, which directly sprays water to inlet air and forms desired cool air prior to distributing the cool air to a target room. On the other hand, Korean Patent Laid-open Publication No. 2000-20820 discloses an indirect-type evaporative cooler, which primarily sprays water to processing air, and reduces the temperature of the processing air, and secondarily performs a heat exchanging process of reducing the temperature of inlet air by the low temperature processing air, thus indirectly cooling the inlet air prior to distributing the air to a target room. Korean Patent Laid-open Publication Nos. 1996-38336 and U.S. Pat. No. 4,566,290 each disclose another type of indirect-type evaporative cooler, which primarily reduces the temperature of processing water, and secondarily performs a heat exchanging process of reducing the temperature of inlet air by the low temperature processing water, thus indirectly cooling the inlet air prior to distributing the air to a target room. On the other hand, U.S. Pat. No. 5,664,433 discloses a combined-type evaporative cooler, which reduces the temperature of inlet air through a combined evaporative cooling system, formed by a combination of the direct- and indirect-type evaporative cooling systems.
When a conventional direct-type evaporative cooler is used within a closed room having poor ventilation, moisture is continuously generated from the vaporization process of the cooler and excessively increases the humidity of the room, thus making users in the room feel unpleasant, particularly when the cooler is used in an area of high temperature and high humidity. On the other hand, the indirect-type evaporative coolers do not change the humidity of a target room, thus being capable of distributing desired cool air currents making usersfeel pleasant, different from the direct-type evaporative coolers.
Such conventional evaporative coolers regardless of their types are advantageous in that they effectively conserve energy since they use energy only for operating blower fans during an operation. However, the temperature of cool air formed by the conventional evaporative coolers is undesirably limited by the wet-bulb temperature of inlet air, and so the evaporative coolers limitedly accomplish their desired operational effect in the case of an operation in an area of high temperature and low humidity; but they don""t accomplish the desired operational effect in an area of high humidity.
In addition, a regenerative evaporative cooling system has been proposed, and used in the design of the prior art evaporative coolers. In a cooler using such a regenerative evaporative cooling system, it is ideally possible to reduce the temperature of air to a dew point of inlet air in place of the wet-bulb point of the inlet air. During a summer season of Korea, the dew point of atmospheric air is typically lower than the wet-bulb point of the atmospheric air by about 2xcx9c5xc2x0 C., and so the regenerative evaporative cooler preferably reduces the temperature of cool air to a point lower than that of the other types of conventional evaporative coolers.
FIG. 1a is a view of a conventional regenerative evaporative cooler.
As shown in the drawing, during an operation of the regenerative evaporative cooler, hot inlet air 21 passes through a dry channel 31 of a heat exchanger while being reduced in its temperature through a heat exchanging process to form low temperature primary air 22. The low temperature primary air 22 from the dry channel 31 is partially extracted into the wet channel 33, arranged in parallel to the dry channel 31, and flows in the wet channel 33 in a direction opposite to that of the primary air 22 within the dry channel 31 as shown by the arrow 23 of the drawing. The extracted air 23 flowing in the wet channel 33 is cooled by the vaporization of water 25, thus being further reduced in its temperature. A temperature difference is formed between the two channels 31 and 33. Due to the temperature difference, the wet channel 33 absorbs heat from the dry channel 31, thus reducing the temperature of the air 21 flowing in the dry channel 31. In the above regenerative evaporative cooler, the phase variations of air flowing in the two channels 31 and 33 are shown in the psychrometric temperature-enthalpy chart of FIG. 1b. 
In the psychrometric temperature-enthalpy chart of FIG. 1b, the phase variation of primary air flowing in the dry channel 31 is designated by the reference numeral 61, while the phase variation of extracted air flowing in the wet channel 33 is designated by the reference numeral 62. As shown in the chart of FIG. 1b, the enthalpy variation 64 per unit mass flow rate of the extracted air is larger than the enthalpy variation 63 per unit mass flow rate of the primary air by about 3xcx9c5 times, and so the amount of extracted air, required to accomplish a desired energy balance between the two channels, is preferably set to {fraction (1/3xcx9c1/5)} of the amount of primary air. Therefore, the regenerative evaporative cooler can distribute cool air currents to a target room, with the amount of distributed cool air currents being set to {fraction (2/3xcx9c4/5)} of the primary air. As shown in the chart of FIG. 1b, the regenerative evaporative cooler effectively reduces the temperature of the primary air to the dew point of the primary air. In order to enlarge the temperature difference of the primary air between the inlet and outlet ends of the dry channel, it is preferable to arrange the dry and wet channels for the primary air and extracted air such that the flowing direction of the primary air is completely opposite to that of the extracted air to form countercurrents.
U.S. Pat. No. 5,301,518 discloses a conventional regenerative evaporative cooler. The cooler of 5,301,518 has a plurality of flat panels, separating a dry channel from a wet channel, and accomplishes a heat transfer from the dry channel to the wet channel through the flat panels. Therefore, the flat panels act as heat transfer panels in the regenerative evaporative cooler. In order to reduce a pressure loss caused by an air flow within the channels, the gap between the flat panels is set to about 1xcx9c2 mm, thus forming a narrow gap capable of forming a laminar flow of air within the channels.
In order to improve the operational performance of such regenerative evaporative coolers, it is necessary to allow water to be actively vaporized within the wet channel 33 of FIG. 1a, in addition to accomplishing an effective heat transferbetween the dry channel 31 and the wet channel 33. However,the conventional regenerative evaporative cooler is designed to form a laminar flow of air within its channels by the heat transfer panels arranged with a gap of about 1xcx9c2 mm as described above, and so the cooler regrettably has a low heat transfer rate. It is thus necessary to sufficiently enlarge the size of the heat transfer panels in order to accomplish a desired heat transfer effect. However, when the heat transfer panels are enlarged in their sizes as described above, it is very difficult or almost impossible to maintain the desired gap of 1xcx9c2 mm between the enlarged heat transfer panels. Therefore, the heat transfer panels may be partially brought into contact with each other, or are enlarged in the gaps between them, thus causing an uneven distribution of air flow, reducing the effective heat transfer area and the effective heat transfer rate and reducing the operational performance of the regenerative evaporative coolers.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a regenerative evaporative cooler, which improves the heat transfer rate between the dry and wet channels, in addition to improving the evaporation rate of water within the wet channel, thus accomplishing improved cooling effect, and which minimizes the pressure loss due to air flow within the dry and wet channels, and which enlarges the width of the dry and wet channels to about 5xcx9c20 mm, thus almost completely overcoming the problems experience in the conventional process of manufacturing the regenerative evaporative coolers.
In order to accomplish the above object, the present invention provides a regenerative evaporative cooler, comprising: a regenerative evaporative cooling unit consisting of a dry channel and a wet channel arranged in the cooling unit to closely come into contact with each other, the dry channel being used for allowing primary air to pass through, the wet channel being used for extracting a part of the primary air from the outlet end of the dry channel so as to form extracted air flowing in the wet channel in a direction opposite to the following direction of the primary air, the cooling unit also including a plurality of cooling fins arranged in the dry and wet channels to enhance the heat transfer in the dry channel and to improve both water vaporization efficiency and water vaporization area in the wet channel; a first blower fan used for sucking the primary air into the dry channel of the cooling unit; a second blower fan used for sucking a part of the primary air of the dry channel into the wet channel so as to form the extracted air; and a water supply unit used for feeding water to the wet channel, whereby the extracted air flowing in the wet channel absorbs heat from the dry channel by means of the cooling fin of the wet channel, thus cooling the primary air flowing in the dry channel.
In the regenerative evaporative cooler of this invention, a direct-type evaporative cooling pad is provided at the outlet end of the dry channel for further reducing the temperature of the primary air from the dry channel through a direct-type evaporative cooling process.
In addition, a plurality of water outlet ports are formed on the cooling fin of the wet channel to form a zigzag arrangement, thus uniformly wetting the surface of the cooling fin of the wet channel.
In an embodiment of this invention, the wet channel is arranged to allow the extracted air of the regenerative evaporative cooling unit to flow in a vertical direction, with the water supply unit supplying water to the upper end of the wet channel, thus allowing the water to flow downward due to gravity while uniformly wetting the surface of the cooling fin of the wet channel.
In another embodiment, the wet channel is arranged to allow the extracted air of the regenerative evaporative cooling unit to flow in a direction inclined relative to a vertical direction at a predetermined angle of inclination, with a plurality of water outlet ports being formed on the cooling fin of the wet channel to allow water to uniformly wet the surface of the cooling fin of the wet channel.
In the regenerative evaporative cooler of this invention, the dry and wet channels are fabricated into a unit module used in the cooler, with a cooling capacity of the cooler being adjustable by controlling the number of unit modules included in the cooler.